Serum interleukin 6 (IL-6) as a potential biomarker of disease progression in active pulmonary tuberculosis following anti-tuberculosis drug therapy.

We would like to thank Agilli et al., for their interest on our ecent paper entitled “Alteration of serum inflammatory cytokines n active pulmonary tuberculosis following anti-tuberculosis drug herapy” and appreciate for their thoughtful comments. With great leasure, we would like to address the concers highlighted by gilli et al. and further clarify the readers on our interpretation of he inflammatory cytokine markers in the context of tuberculosis ncluded in that manuscript. We agree with Agilli et al. that the intensity and duration of musle contraction determine the magnitude of increase in plasma IL-6 n exercise. In our study, we quantified the serum levels of differnt inflammatory cytokines in hospitalized TB patients. The reasons or hospital admission were varied and included severe forms of TB, ypoxia, adverse drug reactions to anti-tuberculosis drugs (ATD), urther investigations and also socioeconomic reasons such as inadquate caregiver support at home. Lifestyle during hospitalization as predominantly sedentary and sampling of venous blood was one in all subjects between 10:00 AM and 12:00 AM, when they ere at rest. Therefore, occupation and exercise are factors unlikely o have influenced serum inflammatory cytokine levels, such as IL-6 n these patients. Our data suggested that a lower body mass index (BMI) as associated with the higher systemic levels of inflammatory ytokines prior to the commencement of ATD therapy. The underying reason behind this temporary association could be due to a umber of reasons. Firstly, the reaction of the host immune system o invading Mycobacterium tuberculosis (Mtb) in the form of higher ctivity of inflammatory cytokines including IL-6 (van Lettow et al., 005). Secondly, Mtb infection leads to persistent anorexia and an ncrease catabolism of energy reserve of the host (van Crevel et al., 002; Lee et al., 2013). As the ATD therapy progressed, the sysemic levels of inflammatory cytokines gradually approached to n immune homeostatic level and the association of inflammaory cytokines with BMI weakened. It is likely that an immune omeostatic cytokine level is necessary to achieve the energy omeostasis and support normal metabolism (Djoba Siawaya et al., 009). Hence, the physicians encourage proper nutrition and plenty f rest in TB patients. These practices may unknowingly prevent ny exercise induced alteration in the cytokine levels and thus elp to attain the homeostatic cytokine and energy levels in the atients. Agilli et al. highlighted that in the exercise, IL-6 causes the eleation in serum IL-10 levels, and thus acts as an anti-inflammatory yokine. IL-6 is a pleiotropic cytokine produced by a number of